The invention relates to a circuit arrangement for measuring a mechanical deformation and having a pressure sensor which, under the influence of a mechanical signal, emits an analog deformation-dependent signal.
German Utility Model 81 19 025 discloses a sensor for detecting the pressure of a medium and having at least one element the resistance of which varies under the influence of pressure. As this element, a conventional commercially available resistor component, preferably a carbon-film resistor, a thin-film resistor or a thick-film resistor is used. The elements are preferably disposed in a bridge circuit, and to compensate for temperature factors and to increase the pressure-dependent signal, resistor components having different temperature and pressure coefficients are used. It is also proposed that resistor elements be disposed on a substrate that is elastically deformable in response to pressure, so that the simultaneous action of pressure and expansion or compression of the resistor component cause a signal increase.
In designing circuit arrangements for evaluating sensor signals, it is often necessary to provide suitable measures for temperature compensation. Typically, the temperature characteristic of the output signal of the circuit arrangement is first calculated or plotted. The temperature characteristic can be represented mathematically as a function dependent on the temperature, which in turn can be developed into a power-series expansion. For most technical applications, it is sufficient for the linear member of the temperature characteristic to be compensated for, since the higher-order members are sufficiently small with respect to an allowable tolerance. For high-precision applications, however, provisions must be made to compensate for quadratic and sometimes even higher components of temperature characteristic. The actual compensation is then generally such that a separate temperature-dependent signal is formed within the circuit arrangement, and this signal is suitably added to or subtracted from the output signal.